VS 8/VS 8A Vital Signs Monitor Operator’s Manual 9 - 1
9 Measuring Noninvasive Blood Pressure
(NIBP)
9.1 NIBP Introduction
The monitor uses the oscillometric method for measuring the Non-Invasive Blood
Pressure (NIBP). NIBP measurement is based on the principle that pulsatile blood flow
through an artery creates oscillations of the arterial wall. The oscillometric device uses a
blood pressure cuff to sense these oscillations that appear as tiny pulsations in cuff
pressure.
Two algorithms can be used on the monitor:
■ Inflation: at the inflation stage, the device creates a slow inflation of a cuff while
simultaneously detecting oscillations. As soon as systolic pressure is determined,
the cuff is deflated. The oscillations that appear during inflation increase in
amplitude to a peak amplitude (which approximates to the mean pressure) with
increasing cuff pressure and then decrease in amplitude. If the measurement fails
at the inflation stage, the device will automatically continue the measurement at
deflation stage.
■ Deflation: the device measures the amplitude of pressure changes in the
occluding cuff as the cuff deflates from above systolic pressure. The amplitude
suddenly increases as the pulse breaks through the occlusion in the artery. As the
cuff pressure decreases further, the pulsations increase in amplitude, reach a
maximum (which approximates to the mean pressure), and then diminish.
The oscillometric method measures the mean pressure and determines the systolic and
diastolic pressures.
NIBP measurement adopting inflation algorithm is intended for adult and pediatric
patients, and NIBP measurement adopting deflation algorithm is intended for adult,
pediatric, and neonatal patients.
• Blood pressure measurements determined with this device are equivalent to
those obtained by a trained observer using the cuff/stethoscope
auscultatory method or an intra-arterial blood pressure measurement
device, within the limits prescribed by the American National Standard:
manual, electronic, or automated sphygmomanometers.
• NIBP measurement can be performed during electro-surgery and discharge
of a defibrillator.
• Be sure to select the correct patient category setting for your patient before
NIBP measurement. Do not apply the higher adult settings for pediatric or
neonatal patients. Otherwise, it may present a safety hazard.
• Do not measure NIBP on patients with sickle-cell disease or on the limb
where skin damage has occurred or is expected.
• If your monitor is using inflation algorithm, select cuffs with the
symbol. Using other cuffs may lead to incorrect or failed measurements.
• Use clinical judgment to determine whether to perform frequent unattended
blood pressure measurement on patients with severe blood clotting
disorders because of the risk of hematoma in the limb fitted with the cuff.
• Do not use the NIBP cuff on a limb with an intravenous infusion or arterial
catheter in place. This could cause tissue damage around the catheter when
the infusion is slowed or blocked during cuff inflation.
• Do not apply cuff on the arm on the side of a mastectomy or lymph node
clearance.
• Continuous cuff pressure due to connection tubing kinking may cause blood
flow interference and result in harmful injury to the patient.
• NIBP reading can be affected by the measurement site, the position of the
patient, exercise, or the patient's physiologic condition. If you doubt the NIBP
measurements, determine the patient’s vital signs by alternative means, and
then verify that the monitor is working correctly.
• Devices that exert pressure on tissue have been associated with purpura,
ischemia, and neuropathy. Inspect the application site regularly to ensure
skin quality and inspect the extremity of the cuffed limb for normal color,
warmth and sensitivity. If the skin quality changes, or if the extremity
circulation is being affected, move the cuff to another site or stop the blood
pressure measurement immediately. Check more frequently when making
automatic or STAT measurement. Auto NIBP measurement with one and two
minute intervals is not recommended for extended periods of time.
• Do not modify or replace connectors of the NIBP air hose except with
Mindray-approved connectors.
• Never connect intra-arterial or intra-venous lines, or any other incompatible
connectors to the NIBP hose. This can cause serious injury or death.
• NIBP diagnostic significance must be decided by the hospital’s clinician staff.
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